article: You can be proud of yourselves, even if you can only make one or two of these green changes. The goal here is to limit CO2and other greenhouse gases, which are closely connected to the big problem of global-warming  .
  WAY 1: Bring your own cup to Starbucks. You'll get a 10-cent discount, and it's one less paper cup to end up in a dustbin. The store won't create more waste when they throw away a cup.
  WAY 2: Turn off your computer. If you don't do that, your PC is still using energy. Turning off a monitor   for 40 hours a week may only save $ 5 a month, but it reduces CO
  by 750 pounds.
  WAY 3: Reuse plastic bags. Instead of throwing away 100 billion plastic bags a year, try and get a second, third, or tenth use out of them. Better yet, next time you shop, try a reusable bag. Oil that is used for making just 14 plastic bags would run your car for one mile.
  WAY 4: Use recycled paper in the bathroom. Most of the toilet paper we use is made from trees found in forests. If every family replaced one roll of toilet paper with a recycled one, 424,000 trees would still be standing.
  WAY 5: Plant a tree. Adding green to your garden is beautiful and earth-pleasing. Just one tree will help make cleaner air and save the environment from 5, 000 pounds of hot CO
  each year.
question: What are the uses of planting a tree?
options: To make your garden beautiful To help make cleaner air To save environment All of above